1. FIELD OF THE INVENTION
This invention relates to a cost effective, disposable, safety syringe having a conventional single ended hypodermic needle cannula bonded to and extending axially from a needle hub at the distal end of the syringe cylinder and, more particularly, to means for engaging, retracting, canting and destroying said cannula within the cylinder to form a compact package suitable for handling and disposal while avoiding an accidental needle stick and the possible spread of disease.
2. BACKGROUND ART
Hypodermic syringes are used for a variety of injection procedures including the delivery of medicinal drops to a recipient. However, once the injection procedure is completed and the syringe cylinder emptied, problems may arise as a consequence of failing to properly and adequately dispose of the syringe. By way of example, the syringe may be used to treat a patient having a communicable disease. To prevent reuse, the hypodermic needle cannula is sometimes broken before the syringe is discarded. Health care workers are susceptible to accidental and potential infectious needle sticks due to the careless handling of the needle cannula or disposing of the syringe after use. The resulting mini-accidents caused by an accidental needle stick typically require a blood test for such diseases as AIDS and hepatitis. The corresponding cost and inefficiency of testing health care workers who have received an inadvertent needle stick result in considerable waste, which may be particularly damaging to a health care facility striving for economy and efficiency.
Disposable safety syringes are known in the art which include means by which to withdraw a needle cannula from an axially extended position, at which to administer an injection, to a retracted position shielded within the syringe cylinder. However, such safety syringes are typically characterized by unconventional parts and, therefore, a high cost. By way of example, the use of special cannula designs and complex cannula retaining means increase the cost of manufacture and adversely impact the cost effectiveness of the syringe.
It would be more desirable to combine a conventional needle cannula and know manufacturing techniques with the advantages of a retractable cannula to achieve a cost effective safety syringe.
The following United States patents and applications, which have been or will be assigned to the assignee of the present patent application, disclose a safety syringe having a retractable needle cannula that is releasably retained in an axially extended position between a pair of spring-like jaws:
U.S. Pat. No. 4,909,794 issued Mar. 20, 1990 PA1 U.S. Pat. No. 4,908,022 issued Mar. 13, 1990 PA1 U.S. Pat. No. 4,944,723 issued July 31, 1990 PA1 U.S. Pat. No. 4,808,169 issued Feb. 28, 1989; and PA1 U.S. Pat. No. 4,826,489 issued May 2, 1989.